There are occasions where packers or other tools need to be milled out and yet portions of the tool need to be retained from falling in the hole once enough milling has gone on to release the packer or other tool. In the past such tools have been advanced into the packer bore or an extension to such a packer bore and included a grapple that was forced into the bore. If the packer let go the grapple was cammed outwardly by a series of inclined surfaces with such camming being triggered by the released weight of the remaining packer. The mandrel could be picked up and turned to the right to engage ratchet teeth so that a left hand thread is engaged to allow rotation of the grapple gripping member with respect to the packer bore for a release, if necessary. One such prior design is shown in Streater U.S. Pat. No. 6,681,858.
Streater uses a longitudinally split cylindrically shaped grapple member 106 that rides in a wedge 104. Grapple 106 has a groove 126 through which extends a tab 110. The groove and the tab are in the middle of the cylinder shape with the tab not extending as far out of the groove so that it stays clear of the packer bore. The problem with this design is during an attempt to release the packer by engaging teeth 124 and 134 while rotating to the right. As the grapple 106 which has an exterior left hand thread starts to come out of the packer bore while having torque transmitted into it through tab 110, some of the grapple 106 is still in the packer bore while the tab 110 transmits torque through slot 126 to the remainder of the cylindrically shaped grapple member now free of the packer bore and less resistant to applied torque. What can happen is that a shear failure can occur at the grapple which, in turn, results in getting the whole tool stuck with the part milled out packer.
The CK Packer Milling Tool sold by Baker Oil Tools is a peripheral mill that supports an internal wash pipe that has a grapple at the end. The mill is circulated through the wash pipe and the existing flow picks up cuttings for the return trip to the surface in the annulus. The small clearance between the mill housing and the wash pipe will not allow reverse circulation with cuttings into the mill housing to work nor can this design be simply modified to create a flow passage big enough between the wash pipe and the mill housing to accommodate the mill debris. The Washover Drill Collar Spear also sold by Baker Oil Tools uses gravity to grip the released drill collars by combining slips at the ends of collet fingers driven out by a taper on a mandrel that falls with the drill collars. The slips grab a wash over pipe extending around the slips.
The present invention provides a grapple for a downhole tool being milled out where the grapple members are better supported in a removal attempt when turning to the right. In a preferred embodiment fingers with exterior wickers that form a left hand thread extend from a ring. The wedge assembly has a series of torque fingers that preferably span the length of the grapple wickers and preferable are disposed on opposed sides of the grapple fingers. The ramp adds force to rotate the grapple when it is turned to the right. A reverse circulation pattern is used with the mill to remove and capture cuttings through the mill body in conjunction with the grapple device. These and other features of the present invention will be more readily understood by those skilled in the art from a review of the description of the preferred embodiment and the associated drawings that appear below while recognizing that the appended claims are the full measure of the invention.